Matter and Its Properties · SHS2 Chemistry

Lesson notes

Learning Objectives

Indicator: 2.1.1.LI.4 - Explain bond energy and apply it to determine endothermic and exothermic reactions.

By the end of the lesson, learners can:

Define bond energy and bond dissociation energy and distinguish clearly between the two terms.
Explain that bond breaking is an endothermic process (energy is absorbed) and bond formation is an exothermic process (energy is released).
Calculate the enthalpy change of a reaction using average bond energy values.
Predict whether a reaction is endothermic or exothermic from its calculated enthalpy change.
Justify the choice of fuels used in homes, transport, and industry based on the amount of energy released per unit mass.

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Curriculum details

Strand: Physical Chemistry (Strand 1)
Sub-strand: Matter and Its Properties (1.1)
Content standard: 2.1.1.CS.1 - Demonstrate knowledge and understanding that energy changes occur in chemical reactions as a result of reorganization of atoms at different rates. 2.1.1.LO.1 Describe the different energy changes that occur as a result of reorganization of atoms. 3 Gender Equality and Social Inclusion 4 Socio-Emotional Learning 2.1.1.LO.2 Use the concept of chemical kinetics to explain that chemical reactions proceed at different rates depending on their conditions and design experiment to investigate these conditions.
Indicator: 2.1.1.LI.4 - Explain bond energy and apply it to determine endothermic and exothermic reactions.
Suggested placement: Semester 1, Week 4 (Week 4 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 63

Exemplars (from the NaCCA curriculum)

Talk for Learning Approach: Using think-pair-share approach, distinguish between bond dissociation energy and bond energy
Activity-Based Learning:
- Calculate the enthalpy change of reaction from bond energy values.
- Discuss bond energy as a measure of energy content hence, bond strength.
- Discuss that the amount of energy released per unit mass is a factor in choosing fuel used at home, transport and industry.
Teaching and Learning Materials:
- * Worksheets: for drawing and labelling enthalpy profile diagram. * Worksheets for supporting calculation of standard enthalpy changes. * Worksheets with task on applying Hess' law to calculate enthalpy of reaction. * Calculator * Hot water * Hydrochloric acid * Sodium hydroxide pellets * Thermometer * Copper sulphate * Zinc powder * Virtual lab on calorimetry * Use of gas syringe * Chemical balance * Calcium chloride
- * Probe
- Beakers (100ml and 400ml)
- Ammonium chloride * Calorimetry setup * Conical flask * Beakers * Marble chips * Hydrochloric acids * Kits for sulphur-clock experiment * Kits for investigating effect of of H O 2 2 * Graph sheets
- WEBSITE
- Videos on the topic:khanacademy.org
- catalyst on decomposition
Assessment (2.1.1.AS.4). The document marks these depth-of-knowledge levels for this indicator: Level 4 Extended critical thinking and reasoning.